Recoil assembly for firearm



J. H.JOHNSON ETAL 3,410,175

RECOIL ASSEMBLY FOR FIREARM Nov. 12, 1968 2 Sheets-Sheet 1 Filed Oct. 23, 1965 N m m T5 NNO EHR V0 mi 5 5% a Jf ATTORNEY Nov. 12, 1968 J. H.JOHNSON ETAL 3,410,175

RECOIL ASSEMBLY FOR FIREARM 2 Sheets-Sheet 2 Filed Oct. 23, 1965 w w a V/// //////x G m M w w x 7/ A FIG A TTORNEY United States Patent 3,410,175 RECOIL ASSEMBLY FOR FIREARM James H. Johnson, New Haven and Julius E. Brooks, Branford, Conn., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia Filed Oct. 23, 1965, Ser. No. 505,313 7 Claims. (Cl. 89-159) ABSTRACT OF THE DISCLOSURE A firearm having reduced recoil effects on the shooter including a barrel having relative movement with the stock and a gas operated operating rod movable relative to the barrel and stock and connected to the firing pin and bolt to move the bolt relative to the barrel. A low rate spring is provided between the stock and the bolt and a mechanical damping and spring assembly is provided between the barrel and stock.

This invention relates to new and useful improvements for use in a firearm, and more particularly, to a recoil arrangement for the barrel and operating rod of a firearm.

In firing conventional automatic weapons, even for small numbers of rounds, it has been established that the weapon will tend to climb. This is true even though the firearm has been fitted with compensating devices which tend to minimize the climb of the firearm itself. These compensating devices fail to take into account the fact that the operator of the firearm becomes a part of the firing system when the firearm is held and the system reacts in a manner different from a freely operating firearm. As a consequence, although the compensating devices in the weapon will tend to alleviate any angular displacement of the firearm due to the firing forces, the body of the firer acts as a fulcrum whereby the recoil forces are transmitted directly to the shoulder of the shooter, tending to rotate the upper portion of the shooters torso about his hips.

It will thus be seen that to obtain the theoretically perfect design of a firearm system which has no climb, the forces transmitted to the shooter must be reduced to zero. In the various attempts to reduce such forces, one proposal has been to utilize a sliding barrel and receiver. However, the overall desirable length of the weapon usually imposes a practical limit upon the amount the barrel may move with respect to the firearm frame. Moreover, with a large amount of barrel motion, as in such designs, it is usually necessary that the magazine also be movably mounted. This results in a complex and unwieldy firearm.

It is therefore an object of this invention to provide an improved firearm to reduce the coil effects which are transmitted to the shooter.

It is a more specific object of this invention to provide a firearm wherein the recoil forces are smoothed out over a relatively long period of time.

Yet another object of this invention is to utilize the relatively long stroke of the bolt and operatin rod of a firearm to reduce recoil forces and thereby permit the barrel motion to be limited to the confines dictated by the stock configuration.

Another approach to reduce recoil effects would be to increase the cyclic rate of the firearm. However, such an increase would result in greater vibration within the firearm, and hence greater dispersion of the shots in all directions. Thus, another object of this invention is to reduce the climb of a firearm without increasing the dispersion in other directions.

These and other objects may be accomplished through the provision of a stock having a barrel member disposed therein for relative axial movement therewith and having a receiver portion for reception of bolt means including a firing pin. Operating rod means may be mounted within the stock for relative axial movement with said barrel means and stock means. The operating rod means is operably connected to the firing pin and bolt means whereby rearward motion of the operating rod wil unlock the bolt means from the receiver and permit relative movement of the bolt means with respect to the receiver. A low rate spring is provided between the stock and the bolt means to bias the bolt means and operating rod means forward relative to the barrel means. A mechanical damping and spring assembly is provided between the barrel and stock to dampen the movement of the barrel means in both the forward and rearward axial direction relative to the stock as well as urge it rearwardly a slight distance from the firing position.

This invention may more readily be understood by reference to the following description and to the accompanying drawings in which:

FIGURE 1 is a schematic representative showing the various components of a firearm constructed in accordance with the present invention;

FIGURE 2 is a schematic representative of the interconnection between the operating rod and bolt means of the firearm of FIGURE 1;

FIGURE 3 is a side view partially in section of the preferred form of the combined damping and spring means mounted between the stock and barrel member of FIGURE 1;

FIGURE 4 is a top plan view of the damping and spring means of FIGURE 3;

FIGURE 5 is a force-time diagram contrasting the rearward forces of a conventional firearm with one constructed in accordance with the present invention; and

FIGURE 6 is a velocity-time diagram contrasting the rearward velocity of a conventional firearm with One constructed in accordance with the present invention.

Referring particularly to FIGURE 1, the firearm of the invention comprises generally a hollow frame indicated by 2 having a butt plate 4 secured to one end thereof. A barrel member 6, having a chamber 8 to accommodate a cartridge 10, is mounted within the frame 2 for limited relative movement therewith.

A bolt assembly 14 is mounted within the receiver 12 rearwardly of the barrel member 6. An operating rod 16 is mounted atop the barrel member 6 and is operably connected at one end to the bolt assembly 14. A gas system 18, including a piston member 20 mounted within a suitable cylinder (not shown), is mounted along the length of the barrel member 6 and has a port (not shown) communicating with the bore of the barrel. The gas system 18 serves to accelerate the operating rod 16 in a rearward direction. As the projectile passes the interconnecting port, the forces of the gas generated by the explosion of the cartridge rams the piston 20 rearwardly relative to its cylinder member whereupon the piston member engages the operating rod 16 with sufficient force to accelerate the operating rod rearwardly with respect to the barrel member 6.

A fire control system 22, indicated generally by the outline in FIGURE 1, is mounted in the frame 2 of the firearm in a position to be engaged by the rearward end of the operating rod 16. The first control system 22 is interconnecting with trigger member by suitable linkages and is adapted to engage the sear 24 mounted on the operating rod 16, the fire control system 22 also includes a suitable mechanism to control the type of firing of the firearm, i.e., semiautomatic, fully automatic or controlled burst firing. Since the specific arrangement of the fire control system 22 forms no part of this invention, it has not been shown in detail.

The bolt assembly 14 includes a hollow cylindrical member 26 having lugs 28 adapted to coact with similar lugs 30 on the barrel member 6 to lock the bolt assembly to the barrel member 6. A firing pin 32 is mounted for axial movement within the cylindrical member 26. The firing pin 32 includes a frusto-conical nose portion 34 adapted to be projected through a frusto-conical opening 36 in the breech closure portion 38 of the cylindrical member 26. The firing pin 32 also includes spaced flange members 40 and 42 interconnected by a reduced body portion 44 and an elongated rod portion 46 extending rearwardly from the flange member 42 through opening 48 in the cylindrical member 26. A booster spring 50 is mounted between the flange 42 and the end of the cylindrical member 26 to bias the firing pin 32 into the fired position.

The operating rod 16 is connected to the bolt assembly 14 by means of a downwardly extending lug portion 52 which extends into the space defined by the flange members 40 and 42 on the firing pin 32. The opening 54 in the cylindrical member 26 of the bolt assembly 14 through which the lug 52 extends has a cam surface 56 such that rearward movement of the operating rod 16 with respect to the cylindrical member 26 will tend to rotate the cylindrical member 26 about its longitudinal axis to unlock the bolt assembly 14 from the barrel member 6.

The sear 24 is mounted on the operating rod 16 by a pivot pin 58 and includes a first cam portion 60 extending upwardly from the operating rod 16 and a receiver engaging extension portion 62 extending downwardly from the operating rod 16. The extension portion 62 is adapted to engage the receiver 12 to hold the operating rod 16 and the firing pin 32 in the cocked position as shown in FIGURE 2. Sear 24 may be biased into its cocked position by a suitable spring member 64.

A low rate recoil spring 66 is mounted in the frame member and extends from the butt plate 4 to the end of the rod portion 46 of the firing pin 32 to bias the bolt assembly 14 forwardly relative to the frame 2. A suitable assembly of a barrel control spring 67 and buffer member 68 is mounted between the forward portion of the frame 2 and barrel member 6 to bias the barrel member 6 rearwardly from the cocked position. A suitable muzzle brake 70 may be mounted adjacent the forward end of the barrel member 6.

A preferred embodiment of the barrel control spring 67 and buffer member 68 is shown in FIGURES 3 and 4. A first flat plate member 72 may be provided which is mounted by suitable means to the barrel member 6. The plate member 72 has a slot 74 extending from its forward end to a point short of its rearward end for reception of a second plate member 76 having a similar slot 78. The twoplate members are mounted such that their median planes are perpendicular to each other.

The first plate member 72 includes a first set of abutment projections 82, one extending on each side of the body portion 88 and positioned adjacent the rearward end of the platemember 72, and a second set of abutment projections 84, one also extending from either side of the body portion 88 and positioned adjacent the forward end of the first plate member 72. A coil spring 90 is disposed between the oppositely disposed first set of abutment projections 82 of the first plate member 72 and a set of abutment projections 86 of the second plate mem-' ber 76 and serves to bias the two plate members 72 and 76 apart in a direction parallel to the axis of the spring.

The first plate member 72 includes an opening 92 ad-' jacent its forward portion and an elongated slot 94 adjacent its rear portion. A spring member 96 having offset portions 98 is mounted on the first plate member 72 such that it extends through the opening 92, along both sides of the plate member 72, and has its ends 100 and 102 mounted within the elongated slot 94. The second plate member 76 includes a plurality of detents 104 positioned in its upper surface for engagement by the offset portions 98 in the spring member 96.

The second set of abutment projections 84 on the first plate member 72 serve to contain the spring member 90 when the second plate member 76 is axially withdrawn past the point where its set of projections 86 are coextensive with projections 84 on the first plate member 72. At this point the spring has no effect upon the relative movement of the two plate members with respect to each other. However, the detents in the upper surface of the second plate member 76 are positioned such that they will still be engaged by the offset portions 98 of the spring 96 whereby there will be a damping effect upon the relative movement of the two plate members.

At the beginning of the firing operation, when the operating rod 16 and firing pin 32 are in the cocked position, the barrel 6 is in its forward position with respect to the frame member 2 with the booster spring 50, and barrel control spring 67 compressed. When the trigger member is depressed to actuate the appropriate linkage in the fire control assembly, the sear 24 is rocked out of engagement with the barrel 6. Under the influence of both the recoil spring 66 and booster spring 50, the operating rod 16 moves forward to drive the firing pin 32 into its fired position with the nose portion 34 projecting through the corresponding opening 38 in the breech closure por tion 36 of the bolt assembly. Simultaneously with this action, the barrel 6 will move rearwardly a short distance due to the reaction from the barrel control spring 67, booster spring 50, and gas pressure within the barrel.

When the projectile passes the gas port, the gas system 18 is actuated and the movement of the piston 20 imparts a relatively high rearward velocity to the operating rod. This reaction of the gas system upon the operating rod tends to reverse the rearward motion of the barrel and receiver.

Slightly prior to the exit of the projectile from the muzzle end of the barrel member, the action of muzzle brake 70 combines with the action of the gas system 18 to move the barrel forwardly against the action of the barrel control spring 67 and buffer 68 assembly which serves to halt the forward motion thereof at a point rearward of the firing position.

As the operating rod 16 moves rearwardly it compresses the booster spring 50 and recoil spring 66. Also during this rearward movement, it rotates the bolt 14 to unlock it from the barrel member due to the action of the lug member 52 upon the cam portion 56 of the bolt assembly. During this time there is a loss of energy of the bolt assembly and operating rod due to the combined effects of the compression of the recoil spring 66 and booster spring 50, the impact of the lug member with the end of the cam surface, friction, and rotation of the bolt mem- 'ber relative to the barrel member.

The effort of unlocking the bolt assembly 14 from the barrel member 6 and the rearward force of the barrel control spring 67, combined with the friction between the barrel-receiver and the rearwardly moving operating rod 16 urge the barrel 6 and receiver 12 to the rear during the latter portion of the recoil phase of the operating rod motion. However, the barrel control spring 67 is limited in its action to a relatively short distance, at which point it is arrested and does not contribute to the recoil motion. The accompanying buffer member 68 acts as an energy absorber and arrests the rearward movement of the barrel and receiver within the maximum allowable rearward movement as dictated by the overall size limitations of the stock of the firearm. The buffer device 68 tends to retain the barrel 6 and receiver 12 in its rearward position until it is accelerated forward by the returning bolt assembly and operating rod (it is noted that there will be some very slight movement because of friction as the operating rod moves forward to the firing position).

The return motion of the operating rod 16 and bolt assembly 14 takes place at a slightly lower average rate than its recoil motion because of the accumulated loss of kinetic energy due to friction and the effort of engaging and ramming the incoming cartridge. After the bolt assembly 14 seats the new cartridge, it impacts upon the receiver and tends to move itforward. It continues this forward motion after the firing of the second round although it is limited by the action of the butter member 68 and compression of the barrel control spring 67. Following this, it moves rearwardly again as described above.

FIGURES 5 and 6 show the effect of the above-described recoil system upon the operator of the firearm as compared to a standard conventional firearm. Referring to FIGURE 5, line 106 represents the acceleration of a conventional weapon with reference to time as the first shot is fired. As can be seen, this is a relatively high force over a relatively short period of time. Line 108 shows a similar type force which acts over a short period of time due to the second firing. Since this invention is particularly adapted for use in three round bursts of firing, the forces on the gun after the third shot is fired are of no consequence and accordingly have not been shown in FIGURE 5.

Accordingly to the above-described arrangement of this invention, the forces upon the operator which are trans mitted through the stock of the gun, are relatively low in amplitude but are spread out over a relatively long period of time as indicated by line 110, representing the forces after the first shot and line 112, representing the forces after the second shot. It is noted that the area under graphs 110 and 112 are equal, thereby indicating that the same momentum is transmitted to the shooter for each shot in both the conventional weapon and a weapon constructed in accordance with this invention.

Since acceleration is directly proportional to force, the force time diagram of FIGURE 5 could also be considered an acceleration time diagram. In the use of a conventional weapon, the velocity builds up rapidly during the time the acceleration takes place and then levels off as indicated by the line 114 in FIGURE 6. With the weapon constructed in accordance with the present invention, the velocity will increase during the entire time of acceleration in a manner indicated by line 116. Since the area under the graphs of the velocity-time diagram of FIGURE 6 is representative of the displacement of the weapon, itwill be seen that at the time of the second shot, the displacement of the firearm constructed according to this invention is approximately /2 that of a conventional weapon while after the third shot is fired, the total displacement is /3 that of a conventional weapon.

It will thus be seen that with the above-described arrangement there will be less rearward displacement of the firearm and accordingly less movement of the man-weapon system about the hips of the man, resulting in less vertical dispersion of the shots in a three round burst.

It will be appreciated that various alterations and modifications of the above-described arrangement will readily suggest themselves to those skilled in the art. It is, therefore, intended that the scope of this invention be ascertained from the following claims.

We claim:

1. A firearm comprising a hollow frame, a barrel member mounted within said frame for limited forward and rearward movement relative thereto and having a receiver attached to one end thereof, operating rod means mounted within said frame for movement relative to said barrel member and said frame, bolt means mounted within said receiver for relative movement therewith between a bolt-open position and a bolt-closed position, said bolt means being operable connected to said operating rod means for movement thereby, low rate recoil spring means interposed between said bolt means and said frame to bias said bolt means toward said bolt-closed position, and barrel spring means interposed between said barrel member and said frame to bias said barrel toward a rearward position.

2. The firearm of claim 1 wherein said barrel sprmg means only acts upon said barrel member during a first portion of its rearward movement, and further including damping means for damping the relative motion of the barrel member with respect to said frame and thereby preventing the barrel member and receiver from be ng moved to the limit of its rearward position and impactmg upon said frame.

3. The firearm of claim 1 further including a gas system interposed between said barrel and said operating rod whereby the gas generated during the firing of a cartridge serves to impart a rearward motion to said operating rod with respect to said barrel member.

4. The firearm of claim 3 wherein the relative movement of the operating rod with respect to the frame 18 greater than the relative movement of said barrel member with respect to said frame.

5. The firearm of claim 4 wherein said bolt means includes a firing pin mounted for relative movement therein and spring means interposed between said bolt means and said firing pin to bias said firing pin forwardly relative to said bolt means.

6. The firearm of claim 5 wherein said bolt means includes a cam slot, said firing pin includes spaced flange members, and said operating rod means includes a lug member engaging said cam slot and extending into the space defined by said spaced flange members.

7. The firearm of claim 2 wherein said barrel spring means comprises a first plate member having one end attached to said barrel member and having a longitudinally extending slot therein, a second plate member having one end attached to said frame and having a longitudinally extending slot therein, said plate members being disposed perpendicularly with respect to each other with one being disposed within the slot of the other, sa d first plate member having a first set of abutment projections extending on opposite sides of first plate member adjacent said attached end and a second set of abutment projections extending on opposite sides of said first plate member ad acent said free end, said second plate member having a set of abutment projections adjacent said attached end, and spring means interposed between the first set of abutment projections of said first plate member and the set of abutment projections of said second plate member; and wherein said damping means comprises a spring mounted on said first plate member extending on both sides thereof and having its end portions mounted within an elongated slot, said spring member having offset portions engageable with detents in the surface of the second plate member.

References Cited UNITED STATES PATENTS 858,745 7/1907 McClean 89198 X 922,173 5/1909 Lovelace 89177 X 1,430,661 10/1922 Lewis 89--185 2,093,169 9/1937 Holek 89159 2,146,185 2/1939 Holek 89159 X 2,189,208 2/ 1940 Holland. 2,962,935 12/1960 Hepperle 8944 3,110,221 11/1963 Lochhead 89159 3,110,222 11/1963 Harvey 89-l59 BENJAMIN A. BORCHELT, Primary Examiner.

S. C. BENTLEY, Assistant Examiner. 

